U.S. patent application number 11/210623 was filed with the patent office on 2006-12-07 for method for determining start and end points of regeneration of diesel soot-filtering device.
Invention is credited to Chang Dae Kim.
Application Number | 20060272320 11/210623 |
Document ID | / |
Family ID | 37492758 |
Filed Date | 2006-12-07 |
United States Patent
Application |
20060272320 |
Kind Code |
A1 |
Kim; Chang Dae |
December 7, 2006 |
Method for determining start and end points of regeneration of
diesel soot-filtering device
Abstract
Disclosed herein is a method for determining start and end
points of regeneration of a diesel soot-filtering device, which
measures a value (hereinafter, referred to as "flow resistance
value") obtained by dividing a difference between pressures at
front and rear ends of a diesel soot-filtering device by the flow
rate of exhaust gas so as to determine the degree of accumulated
amount of soot, so that the start and end points of a compulsory
regeneration of the soot-filtering device can be easily
determined.
Inventors: |
Kim; Chang Dae;
(Hwaseong-si, KR) |
Correspondence
Address: |
MORGAN, LEWIS & BOCKIUS LLP (SF)
2 PALO ALTO SQUARE
3000 El Camino Real, Suite 700
PALO ALTO
CA
94306
US
|
Family ID: |
37492758 |
Appl. No.: |
11/210623 |
Filed: |
August 24, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11142116 |
Jun 1, 2005 |
|
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11210623 |
Aug 24, 2005 |
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Current U.S.
Class: |
60/295 ;
60/297 |
Current CPC
Class: |
Y02T 10/47 20130101;
F01N 9/002 20130101; Y02T 10/40 20130101 |
Class at
Publication: |
060/295 ;
060/297 |
International
Class: |
F01N 3/00 20060101
F01N003/00 |
Claims
1. A method for determining start and end points for regeneration
of a diesel soot-filtering device, comprising the steps of:
measuring a flow resistance value varying depending upon an amount
(SL) of soot accumulated in the soot-filtering device regardless of
conditions of an engine and a vehicle; saving the amount (SL) of
accumulated soot and the measured corresponding flow resistance
value (FR1); setting the flow resistance value (FR1) corresponding
to the saved amount (SL) of soot as a reference of the start point
of a compulsory regeneration of the soot-filtering device;
measuring a flow resistance value (FR2) in a real vehicle, and at
the same time, computing and identifying the amount (SL) of soot
corresponding to the measured flow resistance value (FR2); and
comparing the flow resistance value (FR2) in the real vehicle and
the corresponding flow resistance value (FR1) of the identified
amount (SL) of soot, whereby the start and end points of a
compulsory regeneration of the soot-filtering device are
determined, and simultaneously whether the soot-filtering device is
compulsorily regenerated is determined.
2. The method of claim 1, wherein: said saving comprises storing
data in a storage and computation means; said computing and
identifying amount (SL) is performed through said storage and
computation means; and said comparing of flow resistance values
comprises computing and comparing said valves through said storage
and computation means.
3. The method according to claim 2, wherein the storage and
computation means is an ECU, compares the flow resistance value
(FR2) measured in a real vehicle with the previously stored
corresponding flow resistance value (FR1), and when the measured
flow resistance value (FR2) is identical to the previously stored
corresponding flow resistance value (FR1), determines that a
current regeneration start point is the start point of the
compulsory regeneration while compulsorily regenerating the
soot-filtering device.
Description
RELATED APPLICATION
[0001] The present application is a continuation-in-part of U.S.
patent application Ser. No. 11/142,116, filed Jun. 1, 2005, which
claims priority to Korean Application No. 10-2004-0039431, filed
Jun. 1, 2004. The disclosure of each of the above-cited
applications is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a method for determining
start and end points for regeneration of a diesel soot-filtering
device, and, in particular, a method in which a value (hereinafter,
referred to as "flow resistance value") is obtained by dividing a
difference between pressures at front and rear ends of a diesel
soot-filtering device by the flow rate of exhaust gas to determine
the degree of accumulated amount of soot, so that the start and end
points of compulsory regeneration of the soot-filtering device can
be more easily determined.
[0004] 2. Background of the Related Art
[0005] Currently, efforts have been made for the development of a
diesel soot-filtering device (see FIG. 2) so as to cope with a
EURO-IV regulation. Modifications to many systems are required in
order to conform to such regulation. Since it is difficult to
satisfy the requirements of this regulation only with an existing
oxidation catalyst, a novel diesel soot-filtering device is being
developed.
[0006] Specifically, in case of a diesel motor vehicle, a diesel
soot-filtering device may be not installed in a vehicle having a
load capacity of less than 1.7 tons so as to satisfy the
requirements of the EURO-IV regulation. On the contrary, the diesel
soot-filtering device must necessarily be installed in a vehicle
having a load capacity of more than 1.7 tons to satisfy them.
[0007] In order for a diesel motor vehicle to be equipped with a
diesel soot-filtering device, a large amount of engine data and
vehicle data must be secured, and a sufficient time period for
mapping such data is required. How captured soot is effectively
burned for continuous reuse is one factor for the mounting of the
diesel soot-filtering device. Minimum and high-priority test
variables to be previously taken into consideration in order to
develop and equip a diesel soot-filtering device are as
follows:
[0008] (1) Whether the temperature of exhaust gas has risen due to
post-injection of fuel (including advance/retard?)
[0009] (2) Soot compulsory regeneration strategy according to
engine condition
[0010] (3) Checking both the loaded amount of soot and the start
and end points of soot compulsory regeneration
[0011] (4) Technology for preventing uncontrolled burning, etc.
[0012] As mentioned above, in order to manufacture and sell a
diesel motor vehicle, it must meet certain durability and
evaluation tests (European Evaluation Mode: EC mode, US Evaluation
Mode: FTP-75 mode). Further, it is required that various
development logics conform to given conditions and situations on a
real roadway, including basic logic, error logic, soot compulsory
regeneration logic, so as to prevent unexpected trouble.
[0013] Sufficient data is needed for test variables in all the
cases as described above. After grasping the problems associated
with the items (1), (2) and (4), mapping and test data must be
retained sufficiently. But in case of the item (3), although
sufficient test data is retained, accurate amount and the
accumulated extent of soot must be checked in order to usefully
utilize such data. To this end, currently, the amount of soot
accumulated actually in a real vehicle and an engine can be
measured only by using a scale without other separate methods.
[0014] Consequently, during the test of the real vehicle and the
engine, in order to check the start point of soot compulsory
regeneration, it is required that the amount of soot currently
accumulated within the soot-filtering device be measured using a
scale after removing a corresponding soot-filtering device,
followed by re-mounting it so as to proceed the test.
[0015] However, it is nearly impossible to carry out such a process
since the weight of the soot-filtering device generally reaches 12
to 15 kg, and the soot weighs only approximately 1 to 12 g which is
in a relatively very small amount as compared to the weight of the
device, resulting in a significant decrease in accuracy. In
addition, since the weight of the soot varies even in the case
where foreign substances adhere to the outer appearance of the
soot-filtering device while traveling, it is impossible to
accurately measure the weight of the soot in real time.
[0016] The same difficulties arise in an engine test. However, the
engine test undergoes an easier process than that in the vehicle
test. Similarly, in this case, the amount of soot currently
accumulated within the soot-filtering device is measured using a
scale after removing the soot-filtering device, which is the same
as in the vehicle test. That is, the weight of a corresponding
soot-filtering device is measured using a scale after it is
removed, and then the device is re-mounted so as to proceed with
the test. Resultantly, in the case where such a test is repeatedly
performed, the development period will be greatly extended as well
as reliability of data measured will be significantly degraded.
[0017] Since it is difficult to accurately measure the amount of
soot accumulated in the diesel soot-filtering device, the accurate
start point of regeneration for the accumulated soot within the
device cannot be set. A current regeneration logic of the diesel
soot-filtering device is designed such that a post-injection is
used to regenerate the soot at 600.quadrature. only in a condition
mode beyond a certain condition in view of various variables such
as water temperature (over 50.degree.), engine rpm (over 2000
rev/min), vehicle speed, etc.
[0018] However, there remains a need for a method which can
accurately identify the amount of soot accumulated in the diesel
soot-filtering device prior to regeneration and post completion of
the regeneration. Resultantly, since there is not a method for
determining how much soot has been accumulated in the diesel
soot-filtering device, and up to which level the soot can be
eliminated after regenerating the soot at a given temperature, a
situation may occur where it is impossible to identify the
conditions within the soot-filtering device. This results in an
unnecessary waste of fuel, an aggravation in fuel consumption
ratio, and a reduction in durability due to frequent regeneration
of the soot-filtering device.
SUMMARY OF THE INVENTION
[0019] Embodiments of the present invention provide a method for
determining start and end points for regeneration of a diesel
soot-filtering device, which measures a flow resistance value
obtained by dividing a difference between pressures at front and
rear ends of a diesel soot-filtering device by the flow rate of
exhaust gas, depending upon the amount of soot accumulated in the
soot-filtering device regardless of the condition of an engine and
a vehicle so as to determine the degree of accumulated amount of
soot and the measured corresponding flow resistance value. A
software basis may be prepared and the start and end points for
compulsory regeneration of the soot-filtering device can be easily
determined through the later measurement of the flow resistance
value in a real vehicle.
[0020] In exemplary embodiments of a method for determining start
and end points for regeneration of a diesel soot-filtering device
includes measuring a flow resistance value (i.e., a value obtained
by dividing a difference between pressures at front and rear ends
of a diesel soot-filtering device by the flow rate of exhaust gas)
which varies depending upon the amount (SL) of soot accumulated in
the soot-filtering device regardless of the condition of an engine
and a vehicle; storing the amount (SL) of accumulated soot and the
measured corresponding flow resistance value (FR1) in a
storage/computation means; setting the flow resistance value (FR1)
corresponding to the previously stored amount (SL) of soot as a
reference of the start point of compulsory regeneration of the
soot-filtering device; measuring a flow resistance value (FR2) in a
real vehicle, and at the same time, computing and identifying the
amount (SL) of soot corresponding to the measured flow resistance
value (FR2) through the storage/computation means; and
comparing/computing the flow resistance value (FR2) in the real
vehicle and the corresponding flow resistance value (FR1) of the
identified amount (SL) of soot through the storage/computation
means, whereby the start and end points of a compulsory
regeneration of the soot-filtering device are determined, and
simultaneously whether the soot-filtering device is compulsorily
regenerated is determined.
[0021] In a preferred embodiment, the storage/computation means is
an ECU, compares the flow resistance value (FR2) measured in a real
vehicle with the previously stored corresponding flow resistance
value (FR1), and when the measured flow resistance value (FR2) is
identical to the previously stored corresponding flow resistance
value (FR1), determines that a current regeneration start point is
the start point of the compulsory regeneration while compulsorily
regenerating the soot-filtering device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The above and other objects, features and advantages of the
present invention will be apparent from the following detailed
description of the preferred embodiments of the invention in
conjunction with the accompanying drawings, in which:
[0023] FIG. 1 is a flowchart illustrating a method for determining
start and end points for regeneration of a diesel soot-filtering
device according to an embodiment of the present invention;
[0024] FIG. 2 is a schematic view illustrating a diesel
soot-filtering device according to the accumulation of mileage;
[0025] FIG. 3 is a graph illustrating a variation in flow
resistance value (Del.P/Volume Flow) in a vehicle over time at 6
g/L soot loading;
[0026] FIG. 4 is a graph illustrating a variation in flow
resistance value (Del.P/Volume Flow) in a vehicle over time at 8
g/L soot loading;
[0027] FIG. 5 is a graph illustrating a correlation between an
accumulated soot amount, i.e., soot loading and the flow resistance
value; and
[0028] FIGS. 6a and 6b are graphs illustrating a variation in flow
resistance value over time during the compulsory regeneration at
soot loadings of 6 g/L and 8 g/L, respectively.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0029] Reference will now be made in detail to the preferred
embodiment of the present invention with reference to the attached
drawings.
[0030] Referring to FIGS. 1 and 2, a flow resistance value (i.e., a
value obtained by dividing a difference between pressures at front
and rear ends of a diesel soot-filtering device by the flow rate of
exhaust gas) which varies depending upon each amount (SL) of soot
accumulated in the soot-filtering device regardless of the
condition of an engine and a vehicle is measured. The process of
measuring the flow resistance value may include: allowing an ECU to
receive a signal output from a differential pressure sensor
installed at the front and rear ends of the soot-filtering device
so as to calculate a difference between pressures at the front and
rear ends of the diesel soot-filtering device; allowing the ECU to
receive a signal output from a sensor for detecting the intake air
volume and the amount of fuel so as to measure the flow rate of
exhaust gas; and dividing the calculated pressure difference at the
front and rear ends by the measured flow rate of exhaust gas. The
ECU of the present invention may include a processor, memory and
associated hardware and software as may be selected and programmed
by a person of ordinary skill in the art based on the teaching
contained herein.
[0031] As shown in FIG. 3, the variation in a flow resistance value
is represented as a sharp curve (red colored line) depending on
engine rpm and other variables, but is represented as a more stable
curve (blue colored line) after being subjected to filtering by the
ECU. It can be seen from FIG. 3 that the traveling speed of the
vehicle and the engine rpm vary momentarily, and air volume and
fuel amount also vary every moment by being applied with a
transient interval. But the flow resistance value exhibits a width
of uniform variation, which nearly ranges from 0.030 to 0.035. This
means that the amount of soot accumulated in the diesel
soot-filtering device reaches approximately 6 g. The flow
resistance value in a test vehicle shows a uniform range of nearly
0.030 to 0.035 while not varying easily depending on the external
condition of a vehicle.
[0032] As shown in FIG. 4, the flow resistance value corresponding
to 8 g/L soot loading is within a range between 0.0050 and 0.055 or
so. Next, the each amount (SL) of accumulated soot and the measured
corresponding flow resistance value (FR1) are stored in a storage
and computation means, which may be, for example, the ECU described
above, and the flow resistance value (FR1) corresponding to the
previously stored amount (SL) of soot is set as a reference of the
start point of a compulsory regeneration of the soot-filtering
device. In this manner, in a state where the flow resistance value
(FR1) according to each amount of accumulated soot has been
previously stored in the ECU, when a flow resistance value (FR2) in
a real vehicle is measured, it is possible to identify how much
soot is accumulated in the real vehicle. That is, the flow
resistance value (FR2) of a real vehicle is measured, and
simultaneously, the amount (SL) of soot corresponding to the
measured flow resistance value (FR2) is computed and identified by
the ECU. Subsequently, the flow resistance value (FR2) of the real
vehicle and the corresponding flow resistance value (FR1) of the
identified amount (SL) of soot are compared with each other and
computed by the ECU, so that the start and end points of a
compulsory regeneration of the soot-filtering device are
determined, and simultaneously whether the soot-filtering device is
compulsorily regenerated is determined.
[0033] Resultantly, the flow resistance value measured under a real
vehicle condition can be easily obtained through the data of the
ECU, i.e., the previously stored flow resistance value. When
monitoring the measured flow resistance value, it is possible to
grasp a degree of accumulated amount of soot and the start and end
points of regeneration of the diesel soot-filtering device.
[0034] More specifically, the ECU compares the flow resistance
value (FR2) measured in a real vehicle with the flow resistance
value (FR1) previously stored therein. When the measured flow
resistance value (FR2) is identical to the previously stored flow
resistance value (FR1), the ECU determines that a current
regeneration start point is the start point of the compulsory
regeneration while compulsorily regenerating the soot-filtering
device.
[0035] In order to draw a linear graph as in FIG. 5, a
soot-filtering device with an unknown amount of accumulated soot is
installed in a vehicle, and then a flow resistance value
corresponding to the amount of accumulated soot is obtained. When a
linear graph is drawn, a soot-filtering device with an unknown
amount of accumulated soot can be installed in a real vehicle, and
then a flow resistance value corresponding to the amount of
accumulated soot is obtained. Then, the amount of soot accumulated
in the soot-filtering device can be accurately predicted.
[0036] In order to more effectively utilize the flow resistance
value, it is calculated after being subjected to filtering in the
ECU. Thereafter, the flow resistance value can be easily
represented as a real number by multiplying the calculated flow
resistance value by about 100.
[0037] Accordingly, when it is desired to regenerate the
soot-filtering device based on a soot loading of 8 g/L, a flow
resistance value of a real vehicle is measured to be within a range
from 0.050 to 0.055. In this case, the amount of soot corresponding
to the measured flow resistance value is identified by the ECU.
Further, when the flow resistance value of a real vehicle is
identical to or greater than the previously stored flow resistance
value through subsequent computation of the ECU, the ECU starts to
perform a compulsory regeneration of the soot-filtering device.
[0038] Referring to FIG. 6a, it can be seen from the graph that
almost all of accumulated soot is not burnt until about 1200
seconds needed for compulsory regeneration is spent under a
traveling condition of a corresponding vehicle during the
compulsory regeneration at a soot loading of 6 g/L. Referring to
FIG. 6b, it can be seen from the graph that it is necessary to set
combustion time period of about 800 seconds so as to satisfy the
compulsory regeneration requirements during the compulsory
regeneration at a soot loading of 8 g/L.
[0039] Consequently, as shown in FIGS. 6a and 6b, the total time
period required for the compulsory regeneration of the
soot-filtering device can be determined by soot loading. Supposing
that the amount of soot loaded within the soot-filtering device is
regenerated in a unit of g, its flow resistance value is set as the
start point of soot compulsory regeneration of ECU logic. Then,
when a flow resistance value being monitored is shown as a value in
excess of the flow resistance value previously stored in the ECU,
it becomes possible to obviously determine how long the compulsory
regeneration is needed and when the compulsory regeneration will
terminated.
[0040] As described above, according to a method for determining
start and end points of regeneration of a diesel soot-filtering
device of the present invention, a flow resistance value obtained
by dividing a difference between pressures at front and rear ends
of a diesel soot-filtering device by the flow rate of exhaust gas
is measured so as to determine a degree of accumulated amount of
soot and the measured corresponding flow resistance value, so that
the amount of soot loaded in the soot-filtering device can be
easily grasped and the start and end points of a compulsory
regeneration of the soot-filtering device can also be easily
determined based on the amount of soot loaded only through the
later measurement of a flow resistance value in a real vehicle.
[0041] Further, the inventive method can be employed as a software
key for the compulsory regeneration of the diesel soot-filtering
device, and may be utilized as a method for controlling an engine,
a method of predicting the time point for fuel amount determination
and fuel injection by judging the amount of soot accumulated in the
soot-filtering device.
[0042] While the present invention has been described with
reference to the particular illustrative embodiments, it is not to
be restricted by the embodiments but only by the appended claims.
It is to be appreciated that those skilled in the art can change or
modify the embodiments without departing from the scope and spirit
of the present invention.
* * * * *